1. Field of the Invention
The present invention relates to walk-behind electric working machines having a working unit driven by an electric motor.
2. Background Information
Walk-behind electric working machines haven been known, in which a rotary working unit is driven by an electric motor to perform desired soil cultivating work or weeding work (see, for example, Japanese Patent Laid-Open Publication No. HEI-10-136702 and Japanese Patent No. 3182930).
FIGS. 23A–23C hereof show the electric working machine 200 disclosed in the HEI-10-136702 publication, which includes a cultivating shaft 202 mounted to a lower portion of a machine body frame 201, cultivating claws 203 provided on the cultivating shaft 202 and an electric motor (not shown) mounted on an upper portion of the body frame 201. The motor is covered with a cover 204. The electric working machine 200 also includes an operating handle 205 extending rearward from the body frame 201, and a switch case 207 is mounted on a portion of the operating handle 205 adjacent to a right grip 206. Safety lock button 208 and switch lever 209 are mounted on the switch case 207. The switch lever 209 can be operated by the human operator holding the lever while depressing the safety lock button 208 with the thumb of his or her hand grasping the right grip 206. The motor can be rotated only when a micro switch 211 is kept ON via the switch lever 209. Namely, the electric working machine 200 employs a dual operation scheme which, for activation of the motor, requires operation of the switch lever 209 while depressing the safety lock button 208, so that the motor can be activated only when the human operator actually so desires. Each reference numeral 212 represents a wire harness (a group of conductors or leads), and 213 a left grip.
However, in the case of the working machine 200 disclosed in the HEI-10-136702 publication, the human operator has to activate the motor by holding the switch lever 209 with one or more fingers, other than the thumb, of the right hand while holding the left and right grips 213 and 206 with both hands and depressing the safety lock button 208 with the thumb of the right hand; namely, the human operator has to perform, with only the right hand grasping the right grip 206, the two operations of holding the switch lever 209 while depressing the safety lock button 208, which is very troublesome and increases burdens on the human operator. Therefore, there has been a demand for an improved electric working machine which facilitates the two operations for rotating the motor and thereby reduces the burdens on the human operator.
FIG. 24 shows the working machine 300 disclosed in Japanese Patent No. 3182930, in which an electric motor 302 is provided on a machine body frame 301. Working unit cover 303 covering a rotary working unit 304 is disposed underneath the motor 302, and the rotary working unit 304 is rotatably mounted under the cover 303. The disclosed working machine 300 also includes an operating handle 305 extending rearward from a rear end portion of the body frame 301 and provided with an operation panel 306 having a main switch 307. Forward rotation switch 309 is provided near a left grip 308 of the operating handle 305, and a reverse rotation switch 311 is provided near a right grip 310.
The machine body frame 17 includes a cylindrical handle support section 51 and a cylindrical resisting-bar support section 57, both integrally formed therewith, and the handle support section 51 extends rearwardly and upwardly from a rear upper portion of the machine body frame 17 while the resisting-bar support section 57 extends downwardly from a rear upper portion of the machine body frame 17. The operating handle section 18 is secured to the machine body frame 17, by inserting a proximal end portion 122a of the handle post 122 in a tubular portion or supporting pipe 126 of the handle support section 51 and locking it via a locking lever 141 of a handle post locking mechanism 135.
Specifically, the human operator has to disconnect the machine-body-side wire harness segment 312 and the handle-side harness segment 312 by disconnecting the mating connectors and then detaching the operating handle 305 from the body frame 301. Thus disconnecting the connectors requires extra time and labor. Also, the harness segments 312 disconnected at the connectors have to be held together in one place on or near the body frame 301 and in one place on or near the operating handle 305, which would further add to the necessary time and labor.
As one possible way to save the time and labor, there may be used a wireless-type electric working machine capable of wireless communication so that the electric motor can be controlled, in response to operation any of the operating sections on the handle, via wireless communication and hence the operating handle can be readily detached from the body frame 301. However, in the wireless-type electric working machine, even after removable of the operating handle from the machine body, operating any of the operating sections on the handle would transmit, to the machine body, an operation signal that might undesirably activate the motor against intention of the human operator or the like. To avoid such unintended activation of the motor, it is conceivable to provide a main switch on the operating handle so that the electric motor can be prevented from unintended activation while the main switch is OFF. However, the human operator may forget to turn off the main switch after the removable of the operating handle from the machine body frame, in which case the motor would be undesirably activated in response to unintended operation of any of the operating sections of the handle.